Adhesive composition

ABSTRACT

Provided are an adhesive composition and an organic electronic device (OED) including the same, and particularly, an adhesive composition, which may form an encapsulation structure effectively blocking moisture or oxygen flowing into an OED from the outside, thereby ensuring the lifespan of the OED, realize a top-emission OED, and exhibit excellent adhesive durability and reliability, and an OED including the same.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a National Stage Application of InternationalApplication No. PCT/KR2016/003004, filed Mar. 24, 2016, and claims thebenefit of Korean Patent Application No. 10-2015-0040740, filed on Mar.24, 2015, contents of which are incorporated herein by reference intheir entirety for all purposes as if fully set forth below.

BACKGROUND

1. Field of the Invention

The present application relates to an adhesive composition, an organicelectronic device (OED) including the same, and a method ofmanufacturing the OED.

2. Discussion of Related Art

An OED is a device including an organic material layer in which electriccharges are exchanged using holes and electrons, and the OED may be, forexample, a photovoltaic device, a rectifier, a transmitter, or anorganic light emitting diode (OLED).

Among the OEDs, an OLED has lower power consumption and a higherresponse speed, and is more advantageous in reducing the thickness of adisplay device or lighting than a conventional light source. Such anOLED also has excellent space utilization, and is expected to be appliedto various fields including all types of portable devices, monitors,notebook computers and TVs.

For commercialization and expanded use of the OLED, the most criticalproblem is durability. Organic materials and metal electrodes includedin the OLED are very easily oxidized by an external factor, for example,moisture. Therefore, a product including an OLED is very sensitive toenvironmental factors. For this reason, various methods have beensuggested to effectively prevent the permeation of oxygen or moistureinto an OED such as an OLED from the outside.

Patent Document 1 discloses an adhesive capsulation composition film andan organic electroluminescent element, where the composition is apolyisobutylene (PIB)-based pressure-sensitive adhesive and does nothave high processability and has low reliability under ahigh-temperature and high-humidity condition.

PRIOR ART DOCUMENT Patent Document

(Patent Document 1) Korean Unexamined Patent Application Publication No.2008-0088606

SUMMARY OF THE INVENTION

The present application provides an adhesive composition, which can forman encapsulation structure effectively blocking moisture or oxygenflowing into an OED from the outside, thereby ensuring the lifespan ofthe OED, realize a top-emission OED, and exhibit a moisture barrierproperty and excellent durability and reliability at high temperatureand high humidity, and an OED including the same.

The present application relates to an adhesive composition. The adhesivecomposition may be an encapsulation material applied to encapsulate orcapsulate the OED such as an OLED. In one exemplary embodiment, theadhesive composition of the present application may be applied toencapsulate or capsulate at least one of the side surfaces of an organicelectronic element. Therefore, after being applied in capsulation, theadhesive composition may be present at a peripheral portion of the OED.

The term “OED” used herein refers to a product or device having astructure including an organic material layer in which electric chargesare exchanged using holes and electrons between a pair of facingelectrodes, and examples of the OED may include, but the presentapplication is not limited to, a photovoltaic device, a rectifier, atransmitter, and an OLED. In an exemplary embodiment of the presentapplication, the OED may be an OLED.

The exemplary adhesive composition may include an olefin-based resinhaving a water vapor transmission rate (WVTR) of 50 g/m²·day or less, aheat-curable resin, and a photocurable compound. Since using aheat-curable resin and a photocurable compound in addition to anolefin-based resin having a low WVTR, the present application mayexhibit an excellent water barrier performance and provide excellentdurability and reliability at high temperature and high humidity.

Also, to seal the side surfaces of the organic electronic element, aprocess of coating the surfaces with a liquid adhesive composition isperformed. However, conventionally, after coating, there is difficultyin maintaining a desired capsulated shape due to the high fluidity ofthe composition. In the present application, the adhesive compositionthat has been applied to a desired position may be precured by lightirradiation to control fluidity, and then subjected to main curing.Therefore, in the present application, the applied adhesive compositionmay be maintained in the desired capsulated shape before main curing.That is, in the present application, as the adhesive compositionincludes both of the curable resin and the radical photocurablecompound, a double curing method may be introduced, and therefore thefluidity of the adhesive composition can be controlled at hightemperature after coating.

The adhesive composition of the present application may include anolefin-based resin having a WVTR of 50 g/m²·day or less. The adhesivecomposition of the present application may include the olefin-basedresin satisfying the above WVTR range, and when considering that it isapplied to encapsulate or capsulate an OED, it can provide an excellentmoisture barrier property. The term “resin having a WVTR of 50 g/m²·dayor less” used herein may refer to a resin having a WVTR of 50 g/m²·dayor less, measured in a thickness direction of a film when the film isformed in a layer of the resin to a thickness of 100 μm. The WVTR may be50, 40, 30, 20 or 10 g/m²·day or less, measured at 100° F. and arelative humidity of 100%. As the WVTR is lower, a more excellentmoisture barrier property may be exhibited. The lower limit may be, butis not particularly limited to, for example, 0 g/m²·day or 0.1 g/m²·day.

In detail, the exemplary olefin-based resin of the present applicationincludes an olefin-based resin derived from a mixture of monomers, andthe mixture may have an isoolefin monomer component or multiolefinmonomer component having at least 4 to 7 carbon atoms. The isoolefin maybe present in the range of, for example, 70 to 100 wt % or 85 to 99.5 wt% with respect to the total weight of the monomer. Themultiolefin-derived component may be present in the range of 0.5 to 30wt %, 0.5 to 15 wt % or 0.5 to 8 wt %.

The isoolefin may be, for example, isobutylene, 2-methyl-1-butene,3-methyl-1-butene, 2-methyl-2-butene, 1-butene, 2-butene, methyl vinylether, indene, vinyltrimethylsilane, hexene or 4-methyl-1-pentene. Themultiolefin may have 4 to 14 carbon atoms, and may be, for example,isoprene, butadiene, 2,3-dimethyl-1,3-butadiene, myrcene,6,6-dimethyl-fulvene, hexadiene, cyclopentadiene or piperylene. Otherpolymerizable monomers, for example, styrene and dichlorostyrene mayalso be homopolymerized or copolymerized.

In the present application, the olefin-based resin may include anisobutylene-based homopolymer or copolymer. As described above, anisobutylene-based olefin-based resin or polymer may refer to anolefin-based resin or polymer including 70 mol % or more ofisobutylene-derived repeat units and one or more different polymerizableunit.

In the present application, the olefin-based resin may be butyl rubberor branched butyl-like rubber. The exemplary olefin-based resin is aunsaturated butyl rubber such as a copolymer of an olefin or isoolefinand a multiolefin. As the olefin-based resin included in the adhesivecomposition of the present application, poly(isobutylene-co-isoprene),polyisoprene, polybutadiene, polyisobutylene,poly(styrene-co-butadiene), natural rubber, butyl rubber and a mixturethereof may be used. The available olefin-based resin in the presentapplication may be prepared by any of the suitable means known in theart, and the present application is not limited to the method ofpreparing the olefin-based resin.

In one exemplary embodiment, the olefin-based resin may be a lowmolecular weight polyisobutylene resin. For example, the olefin-basedresin may have a weight average molecular weight of 100,000 or less, and500 or more or 55,000 or more. The present application may realize asuitable adhesive composition for coating and capsulating processes bycontrolling the weight average molecular weight of the olefin-basedresin in the above range. The adhesive composition may have a liquidphase, and may be suitably applied to encapsulate side surfaces of thefollowing OED.

Also, in one exemplary embodiment, the olefin-based resin may be a resinhaving one or more reactive functional groups having reactivity with theabove-described heat-curable resin. The reactive functional groupincluded in the olefin-based resin may be a polar functional group. Atype of the reactive functional group is not particularly limited, andmay be, for example, an acid anhydride group, a carboxyl group, an epoxygroup, an amino group, a hydroxyl group, an isocyanate group, anoxazoline group, an oxetane group, a cyanate group, a phenol group, ahydrazide group or an amide group. Examples of the olefin-based resinhaving the reactive functional group may include succinicanhydride-modified polyisobutylene, maleic anhydride-modified liquidpolyisobutylene, maleic anhydride-modified liquid polyisoprene,epoxy-modified polyisoprene, hydroxyl group-modified liquidpolyisoprene, and allyl-modified liquid polyisoprene. The presentapplication may provide an adhesive having properties such as desiredmoisture barrier property and durability and reliability after curing byforming a crosslinked structure between the olefin-based resin and aheat-curable resin that will be described below.

In an exemplary embodiment of the present application, the adhesivecomposition may include a heat-curable resin. The heat-curable resin maybe a resin including one or more heat-curable functional groups. Aspecific type of the curable resin that can be used in the presentapplication is not particularly limited, and for example, variousheat-curable resins known in the art may be used.

In the specification, the term “heat-curable resin” refers to a resinthat can be cured by a suitable heating or aging process, and the term“photocurable resin” used herein refers to a resin that can be cured byirradiation of electromagnetic waves.

In the present application, a specific type of the heat-curable resin isnot particularly limited as long as a resin has the above-describedproperties. For example, the heat-curable resin may have an adhesiveproperty after being cured, and may be a resin including one or moreheat-curable functional groups such as an epoxy group, a glycidyl group,an isocyanate group, a hydroxyl group, a carboxyl group or an amidegroup. Also, specific types of such a resin may include, but are notlimited to, an acrylic resin, a polyester resin, an isocyanate resin,and an epoxy resin, and preferably, an epoxy acrylate or a urethaneacrylate.

In the present application, as the heat-curable resin, an aromatic oraliphatic, or linear or branched epoxy resin may be used. In oneexemplary embodiment of the present application, an epoxy resin maycontain two or more functional groups and have an epoxy equivalentweight of 180 to 1,000 g/eq. Characteristics of a cured product such asadhesive performance and a glass transition temperature may beeffectively maintained by the epoxy resin having the above range of theepoxy equivalent weight. Such an epoxy resin may be one or a mixture oftwo or more of a cresol novolac epoxy resin, a bisphenol A-type epoxyresin, a bisphenol A-type novolac epoxy resin, a phenol novolac epoxyresin, a tetrafunctional epoxy resin, a biphenyl-type epoxy resin, atriphenol methane-type epoxy resin, an alkyl-modified triphenol methaneepoxy resin, a naphthalene-type epoxy resin, a dicyclopentadiene-typeepoxy resin, and a dicyclopentadiene-modified phenol-type epoxy resin.

In the present application, as a curable resin, an epoxy resin having acyclic structure in a molecular structure may be used, and for example,an alicyclic epoxy resin may be used. Since the alicyclic epoxy resinhas excellent compatibility with the olefin-based resin or thephotocurable compound, it is cured without phase separation, andtherefore uniform crosslinks in an adhesive may be realized.

In one exemplary embodiment, the heat-curable resin may be included at10 to 70 parts by weight with respect to 100 parts by weight of theolefin-based resin. Specifically, the heat-curable compound may beincluded at 15 to 65 parts by weight, 20 to 60 parts by weight or 26 to55 parts by weight with respect to 100 parts by weight of theolefin-based resin. The present application may provide an adhesivecomposition having excellent durability and long-term reliability bycontrolling the content of the heat-curable resin within the aboverange.

Also, the adhesive composition may include a heat-curing agent. Asuitable type of heat-curing agent may be selected and used depending onthe type of the heat-curable resin or a functional group included in theheat-curable resin.

In one exemplary embodiment, when the heat-curable resin is an epoxyresin, as a curing agent for an epoxy resin known in the art, forexample, one or two or more of an amine curing agent, an imidazolecuring agent, a phenol curing agent, a phosphorus curing agent and anacid anhydride curing agent may be used, but the present application isnot limited thereto.

In one exemplary embodiment, as the heat-curing agent, an imidazolecompound, which is in a solid phase at room temperature and has amelting point or decomposition temperature of 80° C. or more, may beused. Such a compound may be, for example, 2-methyl imidazole,2-heptadecyl imidazole, 2-phenyl imidazole, 2-phenyl-4-methyl imidazoleor 1-cyanoethyl-2-phenyl imidazole, but the present application is notlimited thereto.

A content of the heat-curing agent may be selected depending on acomposition of the composition, for example, a type or ratio of theheat-curable resin. For example, the heat-curing agent may be includedat 1 to 30 parts by weight, 5 to 28 parts by weight or 5 to 27 parts byweight with respect to 100 parts by weight of the heat-curable resin.The weight ratio may be adjusted according to the type and ratio of theheat-curable resin or a functional group thereof, or a crosslinkingdensity to be realized.

In an exemplary embodiment of the present application, the heat-curingagent may be a latent curing agent such as an imidazole-isocyanuric acidaddition product, an amine-epoxy addition product, a borontrifluoride-amine complex or a capsulated imidazole. That is, a radicalinitiator that will be described below may be a photoradical initiator,and in the present application, light irradiation may be first performedin a curing process for the adhesive composition to control initialfluidity, and the heat-curing agent, as a latent curing agent, may serveto cure a heat-curable resin when heated after the light irradiation.

In an exemplary embodiment of the present application, the adhesivecomposition may include a photocurable compound. The photocurablecompound may be a radical photocurable compound. The radicalphotocurable compound may include, for example, a multifunctionalpolymerizable compound which has high compatibility with theabove-described olefin-based resin and curable resin and is capable offorming a specific crosslinked structure. Also, in one exemplaryembodiment, the crosslinked structure may be a crosslinked structureformed by heating, a crosslinked structure formed by the irradiation ofactive energy rays or a crosslinked structure formed by aging at roomtemperature. Here, in the category of the “active energy rays,”microwaves, infrared (IR) rays, UV (UV) rays, X rays, gamma rays, andparticle beams including alpha-particle beams, proton beams, neutronbeams and electron beams may be included, and generally, UV rays orelectron beams may be used.

In an exemplary embodiment, the radical photocurable compound may be amultifunctional active energy ray-polymerizable compound, which may be,for example, a compound including two or more functional groups capableof participating in polymerization by the irradiation of active energyrays, for example, functional groups including an ethylene-likeunsaturated double bond such as acryloyl groups, methacryloyl groups,acryloyloxy groups or methacryloyloxy groups or functional groups suchas epoxy groups or oxetane groups. In one exemplary embodiment, themultifunctional active energy ray-polymerizable compound may be a bi- orhigher functional compound.

In an exemplary embodiment of the present application, as themultifunctional active energy ray polymerizable compound, for example, amultifunctional acrylate (MFA) may be used.

In an exemplary embodiment of the present application, the radicalphotocurable compound may satisfy Formula 1.

In Formula 1, R₁ is hydrogen or an alkyl group having 1 to 4 carbonatoms, n is an integer of 2 or higher, and X is a residue derived from alinear, branched or cyclic alkyl or alkenyl group having 3 to 30 carbonatoms. Here, when X is a residue derived from a cyclic alkyl or alkenylgroup, X may be a residue derived from a cyclic alkyl or alkenyl grouphaving 3 to 30, 4 to 28, 6 to 28, 8 to 22, or 12 to 20 carbon atoms.Also, when X is a residue derived from a linear alkyl or alkenyl group,X may be a residue derived from a linear alkyl or alkenyl group having 3to 30, 4 to 28, 6 to 25, or 8 to 20 carbon atoms. Also, when X is aresidue derived from a branched alkyl or alkenyl group, X may be aresidue derived from a branched alkyl or alkenyl group having 3 to 30, 4to 28, 5 to 25, or 6 to 20 carbon atoms.

The term “residue derived from an alkyl or alkenyl group” used hereinmay refer to a residue of a specific compound, for example, an alkyl oralkenyl group. In an exemplary embodiment, in Formula 1, when n is 2, Xmay be an alkylene or alkylidene group. Also, when n is 3 or higher, Xmay be an alkyl or alkenyl group from which two or more hydrogen atomsare released and then linked to a (meth)acryloyl group of Formula 1. nmay be one in the range of 2 to 20.

The term “alkyl group” or “alkenyl group” used herein may be, unlessparticularly defined otherwise, an alkyl or alkenyl group having 1 to30, 1 to 25, 1 to 20, 1 to 16, 1 to 12, 1 to 8, or 1 to 4 carbon atoms.The alkyl or alkenyl group may have a linear, branched or cyclicstructure, and may be arbitrarily substituted by one or moresubstituents.

The term “alkylene group” or “alkylidene group” used herein may be,unless particularly defined otherwise, an alkylene or alkylidene grouphaving 2 to 30, 2 to 25, 2 to 20, 2 to 16, 2 to 12, 2 to 10, or 2 to 8carbon atoms. The alkylene or alkylidene group may have a linear,branched or cyclic structure, and may be arbitrarily substituted by oneor more substituents.

The term “alkoxy group” used herein may be, unless particularly definedotherwise, an alkoxy group having 1 to 20, 1 to 16, 1 to 12, 1 to 8, or1 to 4 carbon atoms. The alkoxy group may have a linear, branched orcyclic structure. Also, the alkoxy group may be arbitrarily substitutedby one or more substituents.

The photocurable compound may be included at 10 to 100 parts by weight,10 to 80 parts by weight, 13 to 60 parts by weight, 14 to 40 parts byweight or 14 to 20 parts by weight with respect to 100 parts by weightof the olefin-based resin. The present application may provide a curedproduct of an adhesive by adjusting a content of the photocurablecompound in the above range to maintain a capsulated structure duringprecuring.

In one exemplary embodiment, the multifunctional active energy raypolymerizable compound that can be polymerized by the irradiation ofactive energy rays may be polybutadiene dimethacrylate, 1,4-butanedioldi(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, 1,6-hexanedioldi(meth)acrylate, 1,8-octanediol di(meth)acrylate, 1,12-dodecanedioldi(meth)acrylate, neopentylglycol di(meth)acrylate, dicyclopentanyldi(meth)acrylate, cyclohexane-1,4-dimethanol di(meth)acrylate,tricyclodecanedimethanol (meth)diacrylate, dimethylol dicyclopentanedi(meth)acrylate, neopentyl glycol modified trimethylolpropanedi(meth)acrylate, adamantane di(meth)acrylate, trimethylolpropanetri(meth)acrylate, or mixtures thereof.

In an exemplary embodiment, the adhesive composition may include aradical initiator as well as the photocurable compound. The radicalinitiator may be a photoradical initiator. A specific type of thephotoinitiator may be suitably selected by considering a curing rate andyellowing probability. For example, a benzoin-based,hydroxyketone-based, aminoketone-based or phosphine oxide-basedphotoinitiator may be used, and specifically, benzoin, benzoinmethylether, benzoin ethylether, benzoin isopropylether, benzoinn-butylether, benzoin isobutylether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone,2,2-diethoxy-2-phenylacetophenone,2-hydroxy-2-methyl-1-phenylpropane-1-one, 1-hydroxycyclohexylphenylketone,2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propane-1-one,4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)ketone, benzophenone,p-phenylbenzophenone, 4,4′-diethylaminobenzophenone,dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone,2-t-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone,2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone,2,4-diethylthioxanthone, benzyldimethylketal, acetophenonedimethylketal, p-dimethylamino benzoic acid ester,oligo[2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone] or2,4,6-trimethylbenzoyl-diphenyl-phosphineoxide may be used.

A content of the photoradical initiator may be changed by the type andratio of a functional group of the radical photocurable compound, or acrosslinking density to be realized. For example, the photoradicalinitiator may be mixed at 0.1 to 20 parts by weight or 0.1 to 15 partsby weight with respect to 100 parts by weight of the photocurablecompound. The present application may introduce a suitable crosslinkedstructure to the adhesive composition by controlling the content of thephotoradical initiator in the above range, and therefore the fluiditymay be controlled at high temperature.

In one exemplary embodiment, the adhesive composition of the presentapplication may include 40 to 90 parts by weight of the olefin-basedresin having a WVTR of 50 g/m²·day or less, 5 to 50 parts by weight ofthe heat-curable resin, and 1 to 40 parts by weight of the photocurablecompound. In another exemplary embodiment, the adhesive composition mayinclude 50 to 80 parts by weight of the olefin-based resin having a WVTRof 50 g/m²·day or less, 10 to 40 parts by weight of the heat-curableresin, and 5 to 30 parts by weight of the photocurable compound. Thepresent application may exhibit an excellent moisture barrierperformance and excellent durability and reliability at high temperatureand high humidity by adjusting the content range of each component ofthe adhesive composition as described above.

The adhesive composition of the present application may also include amoisture absorbent. The term “moisture absorbent” used herein may be ageneral term for a component capable of adsorbing or removing moistureor vapor introduced from the outside through a physical or chemicalreaction. That is, the moisture absorbent may refer to a moisturereactive absorbent, a physical absorbent, or a mixture thereof.

The moisture reactive absorbent chemically reacts with vapor, moistureor oxygen flowing into the resin composition or cured product thereof toadsorb the moisture or vapor. The physical absorbent allows to prolong amigration pathway of the moisture or vapor permeating the resincomposition or cured product thereof, and thus may inhibit thepermeation of the moisture or vapor and maximize a barrier propertyagainst the moisture and vapor through a matrix structure of the resincomposition or cured product thereof and an interaction with themoisture reactive absorbent.

A specific type of the moisture absorbent that can be used in thepresent application may be, but is not particularly limited to, forexample, one or a mixture of two or more of a metal oxide, a metal salt,and phosphorus pentoxide (P₂O₅) as a moisture reactive absorbent, andmay be zeolite, zirconia or montmorillonite as a physical absorbent.

Here, specifically, the metal oxide may be lithium oxide (Li₂O), sodiumoxide (Na₂O), barium oxide (BaO), calcium oxide (CaO) or magnesium oxide(MgO), and the metal salt may be, but is not limited to, a sulfate suchas lithium sulfate (Li₂SO₄), sodium sulfate (Na₂SO₄), calcium sulfate(CaSO₄), magnesium sulfate (MgSO₄), cobalt sulfate (CoSO₄), galliumsulfate (Ga₂(SO₄)₃), titanium sulfate (Ti(SO₄)₂), or nickel sulfate(NiSO₄); a metal halide such as calcium chloride (CaCl₂), magnesiumchloride (MgCl₂), strontium chloride (SrCl₂), yttrium chloride (YCl₃),copper chloride (CuCl₂), cesium fluoride (CsF), tantalum fluoride(TaF₅), niobium fluoride (NbF₅), lithium bromide (LiBr), calcium bromide(CaBr₂), cesium bromide (CeBr₃), selenium bromide (SeBr₄), vanadiumbromide (VBr₃), magnesium bromide (MgBr₂), barium iodide (BaI₂), ormagnesium iodide (MgI₂); or a metal chlorate such as barium perchlorate(Ba(ClO₄)₂) or magnesium perchlorate (Mg (ClO₄)₂).

In the present application, the moisture absorbent such as the metaloxide, which has been suitably processed, may be mixed with thecomposition. For example, a grinding process for the moisture absorbentmay be needed, and to this end, three-roll milling, bead milling or ballmilling may be used.

The adhesive composition of the present application may include themoisture absorbent at 5 to 100 parts by weight, 5 to 90 parts by weight,5 to 80 parts by weight or 10 to 50 parts by weight with respect to 100parts by weight of the olefin-based resin. In the adhesive compositionof the present application, the content of the moisture absorbent may becontrolled to be 5 parts by weight or more, so that the adhesivecomposition or cured product thereof may exhibit the excellent moistureand vapor barrier property. Also, as the content of the moistureabsorbent is controlled to be 100 parts by weight or less, when a thinfilm-type encapsulation structure is formed, an excellent moisturebarrier property may be exhibited.

Also, in one exemplary embodiment, the adhesive composition of thepresent application may have a thixotropic index (TI) was calculated byGeneral Equation 1 in the range of 1.35 to 5.T=V _(0.5) /V ₅  [General Equation 1]

In General Equation 1, V_(0.5) is a viscosity of the adhesivecomposition measured using a Brookfield viscometer with an RV-7 spindleat a temperature of 25° C. and a rotational speed of 0.5 rpm, and V₅ isa viscosity of the adhesive composition measured using a Brookfieldviscometer with an RV-7 spindle at a temperature of 25° C. and arotational speed of 5 rpm. Specifically, the thixotropic index (TI) maybe in the range of 1.35 to 5 or 1.39 to 3.3. The term “thixotropy” usedherein may refer to a property of the composition in which there is nofluidity in a stationary state, but there is fluidity when oscillated.

In the present application, as the thixotropic index (TI) of theadhesive composition is controlled as described above, an encapsulationstructure having an excellent moisture barrier property may be providedvia an olefin-based resin and the problem of bubbles flowing into theencapsulation material in a process of encapsulating an organicelectronic element or blocking of a nozzle during coating of thecomposition may be prevented, and thus processability and productivitymay be enhanced.

In one exemplary embodiment, the adhesive composition may have aviscosity, measured with respect to a torque using a Brookfieldviscometer with an RV-7 spindle at a temperature of 25° C. and arotational speed of 0.5 rpm, in the range of 100,000 to 1,000,000 cPs.Specifically, in the present application, the viscosity may be, unlessparticularly defined otherwise, measured using DV-II+Pro as a Brookfieldviscometer with an RV-7 spindle under conditions of a temperature of 25°C. and a rotational speed of 0.5 rpm, and the viscosity range may be100,000 to 1,000,000 cPs, 200,000 to 900,000 cPs or 300,000 to 800,000cPs. As the viscosity of the composition at room temperature iscontrolled to be 100,000 cPs or more, the precipitation of a materialpresent in the composition, for example, a moisture absorbent or aninorganic filler can be prevented, and a desired shape of encapsulationstructure can be formed and maintained by coating a desired positionwith the composition.

In one exemplary embodiment, the adhesive composition may furtherinclude an inorganic filler. The filler, other than the above-describedmoisture absorbent, may be included to control the thixotropic index(TI) of the adhesive composition. As described above, the thixotropicindex (TI) of the adhesive composition needs to be controlled within aspecific range. A method of controlling the thixotropic index (TI)within the above range is not particularly limited, but may use anadequate amount of the inorganic filler. A specific type of the fillerthat can be used in the present application may be, but is notparticularly limited to, for example, one or a mixture of two or more ofclay, talc, alumina, calcium carbonate and silica.

Also, to increase coupling efficiency between a filler and an organicbinder, the present application may use a product which is subjected tosurface treatment with an organic material as the filler, or furtherinclude a coupling agent.

The adhesive composition of the present application may include theinorganic filler at 0 to 50 parts by weight, 1 to 40 parts by weight, or1 to 20 parts by weight with respect to 100 parts by weight of theolefin-based resin. The present application may provide an encapsulationstructure having excellent moisture or vapor barrier property andmechanical property by controlling the content of the inorganic fillerto be, preferably, 1 part by weight or more. Also, the presentapplication may provide a cured product exhibiting an excellent moisturebarrier property even when formed in a thin film by controlling thecontent of the inorganic filler to 50 parts by weight or less.

Also, the inorganic filler may have a BET surface area in the range of35 to 500 m²/g, 40 to 400 m²/g, 50 to 300 m²/g or 60 to 200 m²/g. Thespecific surface area is measured using a BET method, specifically, byadding 1 g of a sample of the inorganic filler into a tube and thenmeasuring a specific surface area at −195° C. using ASAP2020(Micromeritics, US) without pretreatment. The same sample may besubjected to such measurement 3 times, thereby obtaining an averagevalue. The present application may provide an encapsulation material forfacilitating the realization of a desired encapsulation structure in thepresent application by adjusting the specific surface area of theinorganic filler within the above range.

In the adhesive composition of the present application, in addition tothe above-described components, various additives may be includedwithout affecting the above-described effects of the presentapplication. For example, the resin composition may include a defoamingagent, a coupling agent, a tackifier, a UV stabilizer or an antioxidantat a proper range of content according to desired physical properties.In one exemplary embodiment, the adhesive composition may furtherinclude a defoaming agent. As the present application includes adefoaming agent, a defoaming property is realized in the above-describedcoating process of the adhesive composition, and thus a reliableencapsulation structure may be provided. Also, as long as the physicalproperties of the adhesive composition required in the presentapplication are satisfied, the type of a defoaming agent is notparticularly limited.

In one exemplary embodiment, the adhesive composition may be a liquid atroom temperature, for example, about 25° C. In an exemplary embodimentof the present application, the adhesive composition may be asolventless-type liquid. Here, the photocurable compound may be appliedas a reactive diluent in the solventless-type liquid composition. Theadhesive composition may be applied to encapsulate an organic electronicelement, and specifically, to encapsulate the side surfaces of theorganic electronic element. In the present application, since theadhesive composition is a liquid at room temperature, the element may beencapsulated by a method of coating the side surfaces of the organicelectronic element with the composition.

The exemplary adhesive composition may have a viscosity of 700 to 5,000Pa·s after light irradiation. Within the above range of viscosity, theadhesive composition may maintain a desired shape of the encapsulationstructure. In one exemplary embodiment, the viscosity of the adhesivecomposition may be measured after the adhesive composition is irradiatedwith light in an UV-A wavelength range at a dose of 3 J/cm². Also, theviscosity of the adhesive composition may be the viscosity measured withrespect to shear stress under conditions of a temperature of 25° C., astrain of 10% and a frequency of 1 Hz. In one exemplary embodiment, theviscosity of the composition may be 700 to 4,000 Pa·s, 800 to 3,000 Pa·sor 900 to 2,000 Pa·s.

The term “UV-A wavelength range” used herein may refer to the wavelengthrange of 315 to 400 nm. Specifically, in the specification, the lighthaving the UV-A wavelength range may refer to light having any onewavelength in the range of 315 to 400 nm, or light having two or morewavelengths in the range of 315 to 400 nm.

In an exemplary embodiment of the present application, the adhesivecomposition may be heated after the light irradiation to perform maincuring, resulting in an encapsulation structure of an OED. Theheat-curing may be performed at 40 to 100° C. To form the encapsulationstructure, the adhesive composition needs physical properties such thatmain curing can be performed without a change in a shape of theUV-precured composition even at the high curing temperature. That is, itis necessary to prevent the phenomenon of diffusing the adhesivecomposition at high temperature. In one exemplary embodiment, theadhesive composition may be precured by irradiation of light in the UV-Awavelength range at a dose of 3 J/cm² as described above, and theprecured resin composition may have a viscosity of 500 to 2,000 Pa·s,which is measured with respect to shear stress under conditions of atemperature of 80° C., a strain of 10% and a frequency of 1 Hz. Theviscosity may be, for example, 500 to 1,800 Pa·s, 500 to 1,600 Pa·s or600 to 1,500 Pa·s. The adhesive composition of the present applicationmay satisfy the above range of viscosity, and therefore may beeffectively applied to encapsulate the side surfaces of an OED.

The present application also relates to an OED. The exemplary OED mayinclude, as shown in FIG. 1, a substrate 21; an organic electronicelement 23 formed on the substrate 21; and a side encapsulation layer 10formed on a peripheral portion of the substrate 21 to surround sidesurfaces of the organic electronic element 23, and including theabove-described adhesive composition. Also, the exemplary OED mayfurther include a entire encapsulation layer 11 covering the entiresurface of the organic electronic element 23.

The entire encapsulation layer and the side encapsulation layer may beformed in the same plane. Here, the term “same” used herein may besubstantially the same. For example, the expression “substantially thesame” in the same plane means that there may be an error of ±5 or ±1 μmin a thickness direction. The entire encapsulation layer may encapsulatethe top surface of the element, or encapsulate the side surfaces of theelement as well as the top surface thereof. The side encapsulation layermay be formed on the side surfaces of the element, but may not be indirect contact with the side surfaces of the organic electronic element.For example, the organic electronic element may be encapsulated suchthat the entire encapsulation layer may be in direct contact with thetop and side surfaces of the element. That is, the side encapsulationlayer may not be in contact with the element, but may be disposed on theperipheral portion of the substrate in the plan view of the OED.

The term “peripheral portion” used herein refers to an edge. That is, aperipheral portion of the substrate may refer to an edge of thesubstrate.

A material for constituting the side encapsulation layer may include,but is not particularly limited to, the above-described adhesivecomposition.

Meanwhile, the entire encapsulation layer may include an encapsulationresin, and the encapsulation resin may be an acrylic resin, an epoxyresin, a silicone resin, a fluorine resin, a styrene resin, a polyolefinresin, a thermoplastic elastomer, a polyoxyalkylene resin, a polyesterresin, a polyvinyl chloride resin, a polycarbonate resin, apolyphenylenesulfide resin, a polyamide resin or a mixture thereof. Acomponent for constituting the entire encapsulation layer may be thesame as or different from the above-described adhesive composition.However, since the entire encapsulation layer is in direct contact withthe element, the entire encapsulation layer may not include or mayinclude a small amount of the above-described moisture absorbent. Forexample, the entire encapsulation layer may be included at 0 to 20 partsby weight with respect to 100 parts by weight of the encapsulationresin.

In one exemplary embodiment, the organic electronic element may includea reflective electrode layer formed on a substrate, an organic layerformed on the reflective electrode layer and at least including anemitting layer, and a transparent electrode layer formed on the organiclayer.

In the present application, the organic electronic element 23 may be anOLED.

In one exemplary embodiment, the OED according to the presentapplication may be, but is not limited to, a top-emission OED or abottom-emission OED.

The OED may further include a protective film for protecting the organicelectronic element between the above-described entire encapsulationlayer or side encapsulation layer and the organic electronic element.

Also, the present application relates to a method of manufacturing anOED.

In one exemplary embodiment, the manufacturing method may includeapplying the above-described adhesive composition to a peripheralportion of a substrate 21 on which an organic electronic element 23 isformed to surround side surfaces of the organic electronic element 23.The application of the adhesive composition may be a step for formingthe above-described side encapsulation layer 10.

Here, the substrate 21 on which the organic electronic element 23 isformed may be manufactured by forming a reflective electrode or atransparent electrode on the substrate 21 such as a glass or film byvacuum deposition or sputtering, and forming an organic material layeron the reflective electrode. The organic material layer may include ahole injection layer, a hole transport layer, an emitting layer, anelectron injection layer and/or an electron transport layer.Subsequently, a second electrode may be further formed on the organicmaterial layer. The second electrode may be a transparent electrode or areflective electrode. Afterward, the above-described side encapsulationlayer 10 is applied to the peripheral portion of the substrate 21 tocover the side surfaces of the organic electronic element 23. Here, amethod of forming the side encapsulation layer 10 is not particularlylimited, and may use a technique such as screen printing or dispensercoating to coat the side surfaces of the substrate 21 with theabove-described adhesive composition. Also, a entire encapsulation layer11 for encapsulating the entire surface of the organic electronicelement 23 may be applied. A method of forming the entire encapsulationlayer 11 may use a technique known in the art, for example, one dropfilling.

Also, in the present application, a curing process may be performed onthe full or side encapsulation layer for encapsulating an OED, and sucha curing process (main curing) may be performed in, for example, aheating chamber or a UV chamber, and preferably performed in bothchambers. Conditions for the main curing may be suitably selectedaccording to the stability of an OED.

In one exemplary embodiment, the side encapsulation layer may be formedby coating of the above-described adhesive composition, and then thecomposition may be irradiated with light, thereby inducing crosslinking.The light irradiation may include irradiating the composition with lightin the UV-A wavelength range at a dose of 0.3 to 6 J/cm² or 0.5 to 4J/cm². As described above, a basic shape of the encapsulation structuremay be realized by precuring through light irradiation.

In one exemplary embodiment, the manufacturing method may furtherinclude heat-curing the precured adhesive composition at a temperatureof 40 to 100° C. for 1 to 24 hours, 1 to 20 hours, 1 to 10 hours or 1 to5 hours after the light irradiation. Through the heating step, theadhesive composition may be subjected to main curing.

Effect

The present application provides an adhesive composition, which can forma structure for effectively blocking moisture or oxygen flowing into anOED from the outside, thereby ensuring the lifespan of an OED, realize atop-emission OED, and exhibit a moisture barrier property and excellentadhesive durability and reliability, and an OED including the same.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an OED according to an exemplaryembodiment of the present application.

EXPLANATION OF REFERENCE NUMERALS

1: adhesive

10: side encapsulation layer

11: entire encapsulation layer

21: substrate

22: cover substrate

23: organic electronic element

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, the present application will be described in further detailwith reference to examples according to the present application andcomparative examples not according to the present application, and thescope of the present application is not limited to the followingexamples.

EXAMPLE 1

A polyisobutylene resin (DAELIM, PB2400, Mn=2,400 g/mol, Mw=4,300 g/mol)as an olefin-based resin, an alicyclic epoxy resin (Mitsubishi Chemical,YX8000, epoxy equivalent weight: 205 g/eq, viscosity: 18500 cPs) as aheat-curable resin and trimethylol propane triacrylate (Sartomer, SR351)as a photocurable compound were put into a mixing vessel in a weightratio of 60:30:10 (PB2400:YX8000:SR351) at room temperature. As aradical initiator, 1 part by weight ofbis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide (Irgacure 819, BASF)was put into the vessel with respect to 100 parts by weight of the maincomponents (the olefin-based resin, the heat-curable resin and thephotocurable compound), as a heat-curing agent, 5 parts by weight of animidazole-based curing agent (2P4MZ, 2-phenyl-4-methylimidazole,Shikoku) was put into vessel with respect to 100 parts by weight of themain components, and 1 part by weight of an epoxy silane(glycidyloxypropyl trimethoxysilane, KBM403, Shinetsu) was put into thevessel with respect to 100 parts by weight of the main components. Also,as an inorganic filler, 3 parts by weight of fumed silica (Aerosil,Evonik, R805, particle size: about 10˜20 nm) was put into the vesselwith respect to 100 parts by weight of the main components. Meanwhile,as a moisture absorbent, 20 parts by weight of calcium oxide (CaO,Aldrich, particle size: 1˜5 μm) was further put into the vessel withrespect to 100 parts by weight of the main components.

A homogeneous composition solution was prepared in the mixing vesselusing a planetary mixer (Kurabo Industries, KK-250s).

EXAMPLE 2

An adhesive composition was prepared by the same method as described inExample 1, except that an acid anhydride-modified polyisobutylene (BASF,Glissopal SA, Mn 1000 g/mol, Mw=970 g/mol) was used as an olefin-basedresin, the olefin-based resin, a heat-curable resin and a photocurablecompound were put into a mixing vessel in a weight ratio of 70:20:10,and 25 parts by weight of a moisture absorbent and 2 parts by weight ofan inorganic filler were put into the mixing vessel.

EXAMPLE 3

An adhesive composition was prepared by the same method as described inExample 2, except that 30 parts by weight of a moisture absorbent wasput into a mixing vessel.

EXAMPLE 4

An adhesive composition was prepared by the same method as described inExample 1, except that an acid anhydride-modified polyisobutylene (BASF,Glissopal SA, Mn 1000 g/mol) as an olefin-based resin, an aromatic epoxyresin (DIC, Epiclon 850, epoxy equivalent weight: 184 g/eq, viscosity:11000 cPs) as a heat-curable resin and trimethylol propane triacrylate(Sartomer, SR351) as a photocurable compound were put into a mixingvessel in a weight ratio of 60:30:10 (PB2400:Epiclon 850:SR351).

COMPARATIVE EXAMPLE 1

An alicyclic epoxy resin (Mitsubishi Chemical, YX8000, epoxy equivalentweight: 205 g/eq, viscosity: 18500 cPs) and an aromatic epoxy resin(DIC, Epiclon 850, epoxy equivalent weight: 184 g/eq, viscosity: 11000cPs) were put into a mixing vessel in a weight ratio of 50:50(YX8000:Epiclon850) at room temperature. 5 parts by weight of animidazole-based curing agent (2P4MZ, 2-phenyl-4-methylimidazole,Shikoku) as a heat-curing agent was put into the vessel with respect to100 parts by weight of the main components (the alicyclic epoxy resinand the aromatic epoxy resin), and 1 part by weight of an epoxy silane(glycidyloxypropyl trimethoxysilane, KBM403, Shinetsu) was put into thevessel with respect to 100 parts by weight of the main components. Also,3 parts by weight of fumed silica (Aerosil, Evonik, R805, particle size:10˜20 nm) as an inorganic filler was put into the vessel with respect to100 parts by weight of the main components. Meanwhile, 20 parts byweight of calcium oxide (CaO, Aldrich, particle size: 1˜5 μm) as amoisture absorbent was further put into the vessel with respect to 100parts by weight of the main components.

A homogeneous composition solution was prepared in the mixing vesselusing a planetary mixer (Kurabo Industries, KK-250s).

COMPARATIVE EXAMPLE 2

An adhesive composition was prepared by the same method as described inComparative Example 1, except that a polyisobutylene resin (DAELIMPB2400, Mn=2,400 g/mol) as an olefin-based resin, instead of an aromaticepoxy resin, and an alicyclic epoxy resin (Mitsubishi Chemical, YX8000,epoxy equivalent weight: 205 g/eq, viscosity: 18500 cPs) as aheat-curable resin were put into a mixing vessel in a weight ratio of70:30 (PB2400:YX8000).

COMPARATIVE EXAMPLE 3

A polyisobutylene resin (DAELIM PB2400, Mn=2,400 g/mol) as anolefin-based resin and trimethylol propane triacrylate (Sartomer, SR351)as a photocurable compound were put into a mixing vessel in a weightratio of 70:30 (PB2400:SR351) at room temperature. As a radicalinitiator, 1 part by weight ofbis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide (Irgacure 819, BASF)was put into the vessel with respect to 100 parts by weight of the maincomponents (the olefin-based rein and the photocurable compound), and 1part by weight of an epoxy silane (glycidyloxypropyl trimethoxysilane,KBM403, Shinetsu) was put into the vessel with respect to 100 parts byweight of the main components. Also, as an inorganic filler, 3 parts byweight of fumed silica (Aerosil, Evonik, R805, particle size 10˜20 nm)was put into the vessel with respect to 100 parts by weight of the maincomponents. Meanwhile, as a moisture absorbent, 20 parts by weight ofcalcium oxide (CaO, Aldrich, particle size: 1˜5 μm) was further put intothe vessel with respect to 100 parts by weight of the main components.

A homogeneous composition solution was prepared in the mixing vesselusing a planetary mixer (Kurabo Industries, KK-250s).

Hereinafter, physical properties in the examples and comparativeexamples were evaluated by the following methods.

1. Adhesive Durability and Reliability at High Temperature and HighHumidity

The adhesive composition prepared in each one of the examples and thecomparative examples was injected into a syringe, defoamed, applied to aperipheral portion (edge) of a glass substrate, and laminated with acover substrate. Subsequently, the coated adhesive composition wasirradiated with light in the UV-A wavelength range at a dose of 5 J/cm²and heated at 100° C. for 3 hours, resulting in preparing a specimen.Afterward, the specimen was maintained in a constant temperature andhumidity chamber at 85° C. and 85% for about 100 hours, and observedwhether or not to have lifting, bubbles or haze at an interface betweenthe glass substrate and the adhesive. With the naked eye, when at leastone lifting, bubbles or haze was observed at the interface between theglass substrate and the adhesive, it was denoted as X, when lifting,bubbles or haze was partially observed, it was denoted as A, and whenthere was no lifting, bubbles or haze, it was denoted as O.

2. Evaluation of Accelerating Lifespan of Element

A calcium test was performed to indirectly evaluate the lifespan of anOELD to which one of the adhesive compositions in the examples and thecomparative examples under accelerating conditions. In detail, sevenspots of calcium (Ca) each having a size of 5 mm×5 mm and to a thicknessof 100 nm were deposited on a glass substrate having a size of 100mm×100 mm, the adhesive composition prepared in the example or theexemplary embodiment was applied to coat a peripheral portion (edge) ofthe substrate 3 mm apart from the calcium-deposited portion using adispenser, and each of the calcium-deposited portions on the substratewas laminated with a cover glass and pressed so that the adhesivecomposition had a thickness of 3 mm, and then irradiated with light inthe UV-A wavelength range at a dose of 5 J/cm². Afterward, the substratewas cured in a high temperature dryer at 100° C. for 3 hours, and theencapsulated calcium (Ca) specimen was cut into pieces in a size of 14mm×14 mm. The obtained specimens were maintained in a constanttemperature and humidity chamber in an environment of 85° C. and 85%R.H. for 1000 hours. Here, when the calcium-deposited portion was alittle eroded by an oxidation reaction caused by moisture permeation, itwas denoted as X, some of the calcium-deposited portions were eroded, itwas denoted as Δ, and when there was no change in the calcium-depositedportions, it was denoted as O.

TABLE 1 High temperature high Evaluation of humidity adhesiveaccelerating durability and reliability lifespan of element Example1 ◯ ◯Example2 ◯ ◯ Example3 ◯ ◯ Example4 Δ Δ Comparative X X Example1Comparative ◯ X Example2 Comparative X X Example3

What is claimed is:
 1. An adhesive composition for encapsulating anorganic electronic element, comprising: an olefin-based resin having awater vapor transmission rate (WVTR) of 50 g/m²·day or less; aheat-curable resin; and a photocurable compound, wherein theolefin-based resin has a weight average molecular weight of less than100,000, wherein the olefin-based resin, the heat-curable resin and thephotocurable compound are comprises at 40 to 90 parts by weight, 5 to 50parts by weight and 1 to 40 parts by weight, respectively, and whereinthe adhesive composition is a solventless liquid at 25° C.
 2. Theadhesive composition of claim 1, wherein the olefin-based resin has oneor more reactive functional groups having reactivity with theheat-curable resin.
 3. The adhesive composition of claim 2, wherein thefunctional group having reactivity with the heat-curable resin is anacid anhydride group, a carboxyl group, an epoxy group, an amino group,a hydroxyl group, an isocyanate group, an oxazoline group, an oxetanegroup, a cyanate group, a phenol group, a hydrazide group or an amidegroup.
 4. The adhesive composition of claim 1, wherein heat-curableresin comprises at least one heat-curable functional group.
 5. Theadhesive composition of claim 4, wherein the heat-curable functionalgroup comprises an epoxy group, an isocyanate group, a hydroxyl group, acarboxyl group or an amide group.
 6. The adhesive composition of claim1, wherein the heat-curable resin is comprised at 10 to 70 parts byweight with respect to 100 parts by weight of the olefin-based resin. 7.The adhesive composition of claim 1, further comprising: a heat-curingagent.
 8. The adhesive composition of claim 7, wherein the heat-curingagent is a latent curing agent.
 9. The adhesive composition of claim 8,wherein the heat-curing agent is comprised at 1 to 30 parts by weightwith respect to 100 parts by weight of the heat-curable resin.
 10. Theadhesive composition of claim 1, wherein the photocurable compound is amultifunctional active energy ray-polymerizable compound.
 11. Theadhesive composition of claim 1, wherein the photocurable compound iscomprised at 10 to 100 parts by weight with respect to 100 parts byweight of the olefin-based resin.
 12. The adhesive composition of claim1, further comprising: a photoradical initiator at 0.1 to 20 parts byweight with respect to 100 parts by weight of the photocurable compound.13. The adhesive composition of claim 1, further comprising: a moistureabsorbent.
 14. The adhesive composition of claim 13, wherein themoisture absorbent is included at 5 to 100 parts by weight with respectto 100 parts by weight of the olefin-based resin.
 15. An organicelectronic device, comprising: a substrate; an organic electronicelement formed on the substrate; and a side encapsulation layer formedon a peripheral portion of the substrate to surround side surfaces ofthe organic electronic element, and comprising the adhesive compositionof claim
 1. 16. The organic electronic device of claim 15, furthercomprising: an entire encapsulation layer for covering the entiresurface of the organic electronic element, wherein the entireencapsulation layer is present in the same plane as the sideencapsulation layer.
 17. A method of manufacturing an organic electronicdevice, comprising: applying the adhesive composition of claim 1 to aperipheral portion of a substrate on which an organic electronic elementis formed to surround side surfaces of the organic electronic element;irradiating the adhesive composition with light; and heating theadhesive composition.